In microscopes, lenses form a central component. They are available with the most varied magnifications and resolutions. Typically, lenses with a greater magnification also have a higher resolution than lenses with a low magnification. For lenses with a particularly high resolution, the space between the lens and the sample is filled with a liquid. This may for example be water or oil. Such lenses are correspondingly also referred to as immersion lenses. By contrast, lenses without immersion are referred to as dry lenses.
In a manual inverted microscope, the user will, prior to using an immersion lens, apply a drop of the immersion liquid onto the lens and/or the sample carrier, subsequently insert the sample carrier into the table and carry out the desired examinations. Upon completion, the sample carrier is removed again and the remaining liquid is removed both from the front of the lens and from the bottom side of the sample carrier. The term sample carrier is here understood to mean both a classical object carrier and any other sample vessels such as microtiter plates, petri dishes and so on. During material examinations, the sample can, under certain circumstances, also be placed directly on the table without a special sample carrier being required.
However, in automated microscopes, a process of this type, where the user has to intervene, is neither desired nor possible. On the one hand it may be that the experiment is not yet finished with the end of the immersion examination, in which case a manual removal of the sample carrier including the subsequent cleaning process would interrupt the automated process. Also, if a plurality of like sample carriers is to be examined one after the other, it is of great disadvantage if a user has to intervene in the device after the examination of each sample carrier. Moreover, automated microscopes frequently include a housing, so that access to the individual components is not always easy.
If this cleaning process is dispensed with, the immersion media would run into the device when the lens is replaced, which can lead to functional incapacity of the entire microscope. In order to passively remove overflowing immersion media, Aquastop solutions exist. Their main purpose, however, is to protect the lens, which is provided with a sheath, on the outside of which the liquid can run off. Subsequently, it is discharged via a hose. However, this device is not suitable for terminating the immersion at the end of the use of the immersion lens.
Various devices have already been described which allow the automatic supply and discharge of immersion media. All of them are based on a cap-like arrangement that is placed on top or on the side of the immersion lens (DE 102005040828, US 2005/0179997, WO 2008028475, DE 10123027). However, these devices can only ever be used for one immersion lens at a time.
DE 102005040828 describes a device wherein the front of the lens is placed on a cylindrical vessel having a supply line and a discharge line, in order to pass immersion liquid into this vessel and subsequently discharge it therefrom. The control takes place either via pumps or via valves. After the use of the lens, the liquid can either run off or is sucked off. The solution is in each case tied to one lens at a time.
US 2005/0179997 describes a system in which it is possible to change from a dry lens to an immersion lens. The immersion liquid is supplied and discharged by means of pumps. Both lenses are arranged next to each other, so that the table has to be moved from one to the other. This solution, too, is tied to one lens.
In known Aquastop solutions, the lens is provided with a protective sheath, so that any overflowing immersion medium can flow off on the outside along the protective sheath and is discharged via a hose system, so that no damage to the lens or to the inside of the microscope is caused. These solutions are directed to the protection of the optical system from escaping immersion media.
The disadvantage all the known solutions have in common is that they are always tied to just one lens. Further, they need a lot of space around the lens. In microscopes, the lenses are as a rule mounted on a revolver, in order to provide the user with as many different lens options as possible. There is then usually only little installation space between the individual lenses. The use of the solutions described in the prior art can then lead to a situation in which the revolver positions next to the immersion lens have to remain free because the immersion caps occupy too much space. If a plurality of immersion lenses is to be used, each of them would then also have to be provided with such a cap, which would restrict the available space even further. Moreover, such a solution would be very expensive.